The male sterility fluctuation of photo-thermo-sensitive genic ma1e sterile〔P(T) GMS〕lines induced by low air temperature is a key problem troubling the application of two-line system hybrid rice. The paper suggests to solve this problem by the breeding approeches, i.e, developing low sterile critical temperature P(T)GMS lines, herbicie resistant restorer lines, herbicide sensitive P(T)GMS lines and tetracycline-conditioned P(T)GMS lines to ensure the hybrid purity; and by the hybrid seed production techniques, i.e, taking the correct procedure of foundation seed production, the suitable district and season for hybrid seed production and the deep irrigation method against cold weather in high summer. 相似文献
1. The fear levels of broilers arriving from slaughter at 4 commercial processing plants were assessed using tonic immobility (TI) tests. The relative effects of selected variables were also examined.
2. Neither the position of the birds on the lorry, nor their sex, nor the ambient temperature nor the identity of the experimeter exerted any significant effects on tonic immobility reactions.
3. Although the longest and shortest immobility responses followed transportation in the fixed crates and metal modules respectively, system comparisons may be confounded by variations in the birds’ genetic and/or experiential backgrounds.
4. Both journey duration and waiting time before transport bore an unambiguous and positive linear relationship with mean TI duration. The duration of transit was the major factor determining fear levels following both commercial and simulated journeys. 相似文献
